The government hoisted the "open for business" sign above the UK , at what was billed as the biggest business conference ever held in Britain.

David Cameron kicked off two weeks of Olympic business summits in the lavish surroundings of Lancaster House, aimed at attracting investment to the UK and promoting British business.

The venue for the "British Business Embassy" was chosen carefully. Built in 1825 by the "grand old" Duke of York, Lancaster House is managed by the Foreign and Commonwealth Office and is about as British as it comes. It just oozes that winning Downton Abbey vibe. The vast mansion, just a short carriage ride from Buckingham Palace, has all the necessary candelabras on the mantelpieces and chandeliers hanging from the ceiling.

But they were nestled alongside pieces from rather more on-trend British designers. There were aluminium and nickel-plated benches extruded by machine and designed by Thomas Heatherwick, a graduate of the Royal College of Art, and silver-studded armchairs by Lee Broom. There were more designer benches in the garden and a curved catwalk snaked across the lawn, along which, Chinese male models will sashay as part of a China-focused summit.

Then there were the showcases to display the best of British: a tartan handbag from Vivienne Westwood sat alongside models of Wallace and Gromit. There were screens showing rolling videos of celebrity British talent, such as Richard Branson and Victoria Beckham, extolling the virtues of this country.

Every delegate was provided with a tablet computer where every item on display was catalogued and described in great detail.

From Saturday, delegates turning up at Lancaster House will be able to take in the views of the beach volleyball competition, taking place just a few strides away in Horse Guards Parade.

On Thursday, just to complete the Olympic atmosphere, the sound of the Chariots of Fire theme by Vangelis drifted through the air while the mayor of London, Boris Johnson, provided a rousing lunchtime speech.

Out on the lawn in the blazing sunshine, Johnson drew comparisons with the last time Britain hosted the Olympic Games in 1948, when the foreign teams had to bring their own food with them. Banging the drum for London, he said: "This is the best, big city on Earth to live in and work in."

Delegates tucked into a light lunch prepared by the Michelin-starred chef Tom Aiken, with ingredients sourced from across the British isles – Loch Duart salmon with a watercress and gem salad and a soft-boiled Clarence Court egg, which apparently have the "brightest, yellowest yolk you could ever imagine". There was Yellison Farm goats' cheese with beetroot, and vanilla cream with apple jelly, made with Cox's apples.

Then it was back to the hall – growing increasingly warm as the 200 business leaders shifted in their seats and the sun streamed through the windows – for more tub-thumping about the UK's life sciences and hi-tech industries.

The roll call of speakers for the day was certainly impressive, with the IMF chief, Christine Lagarde, and Google's chairman, Eric Schmidt, alongside home-grown talent such as Sir Martin Sorrell of WPP and Warren East of ARM. Angel Gurría, secretary general of the OECD thinktank, was among the highlights of the day if only because of his wild gesticulations and cryptic metaphors for the global financial crisis.

The day also offered some respite for the trade minister Lord Green, who is under pressure over his role as chief executive and then chairman at HSBC in the years when, a Senate committee has recently revealed, the bank was laundering money for Mexican drug barons, rogue nations and possibly even terrorists. He had to take to the stage alone as Stuart Gulliver, current chief executive of HSBC, withdrew from the conference after the money-laundering revelations were made.

But Green turned on the charm to welcome delegates to the conference, exchanged a warm handshake with the Bank of England governor, Mervyn King, and closed the conference by offering his mobile phone number to all the delegates. "This is about telling you that Britain is open for business," he said.

And with that the delegates rushed out for some fresh air, and prepared to move on – to Clarence House, home of the Prince of Wales, for a spot of dinner.